1. Field of the Invention
The present invention relates to a blood pressure measuring device, and more particularly to a blood pressure measuring device provided with an automatic cuff winding mechanism for automatically winding a cuff around a living body.
2. Description of the Background Art
To measure a blood pressure value, generally, a cuff provided with a living body pressing fluid bag for pressing an artery located within the living body is wound around the body surface, and arterial pressure pulse waves caused in the artery by inflation/deflation of the living body pressing fluid bag are detected to measure the blood pressure value. Here, the cuff refers to a band-shaped structure having a bladder, which can be wound around a portion of a living body, for use in measurement of arterial pressure of an upper limb, a lower limb or the like by introducing fluid such as gas or liquid into the bladder. Thus, the cuff represents the concept including the living body pressing fluid bag as well as a unit for winding the living body pressing fluid bag around the living body.
In a conventional blood pressure measuring device (hereinafter, also simply referred to as a “blood pressure monitor”), the cuff was wound around the living body by a subject or the like, so that there occurred variation in the cuff winding strength, which caused variation in the blood pressure values measured. Thus, in recent years, blood pressure monitors provided with an automatic cuff winding device have become widespread, which enables automatic winding of the cuff around the living body. With the blood pressure monitor provided with the automatic cuff winding device, constant winding strength is reproduced for each time of measurement, which ensures stable and accurate measurement and also eliminates the burdensome, cuff winding job.
A blood pressure monitor provided with an automatic cuff winding mechanism generally has a hollow opening at a prescribed position of the main unit case into which a portion of the living body is inserted, and a cuff for securing the living body by pressing is disposed on the inner peripheral surface of the hollow opening. The automatic cuff winding mechanism housed in the main unit case is used to wind the cuff around an upper arm, for example, inserted into the hollow opening, to measure a blood pressure value.
The blood pressure monitors each provided with an automatic cuff winding mechanism as described above are disclosed, e.g., in Japanese Patent Laying-Open Nos. 10-314123, 10-314125, and Japanese Utility Model Laying-Open No. 02-135003. The blood pressure monitors disclosed therein, however, pose the following problems.
Firstly, in each of the blood pressure monitors provided with automatic cuff winding mechanisms disclosed in Japanese Patent Laying-Open Nos. 10-314123 and 10-314125, a living body insert portion including a hollow opening into which an arm is inserted is integral with a main unit incorporating a cuff winding mechanism, thereby restricting the posture allowed to a subject at the time of measurement. The posture of a subject upon measurement varies depending on the body type of the subject, the height of a table on which the blood pressure monitor is placed, the height of a chair on which the subject sits, and others. Thus, if the inclination angle of the living body insert portion and the inclination angle of the subject's arm inserted do not match, there occurs a gap between the cuff and the arm, in which case the arm cannot be pressed uniformly, leading to degradation of accuracy in measurement. Further, the subject would feel pain, since he/she needs to keep a constrained posture during the measurement.
In the blood pressure monitor provided with an automatic cuff winding mechanism disclosed in Japanese Utility Model Laying-Open No. 02-135003, the cuff winding mechanism provided in the living body insert portion is supported by a plate spring or a plurality of coil springs, to allow swinging of the winding mechanism itself The hollow opening provided at the living body insert portion, however, is integral with the main unit, so that the angle of insertion of the arm is restricted at the mouth of the living body insert portion, again restricting the posture of a subject at the time of measurement. Although the degree of freedom of the posture upon measurement is somewhat improved compared to the automatic cuff winding mechanism disclosed in Japanese Patent Laying-Open Nos. 10-314123 and 10-314125, the problem has not been solved completely. Further, since the winding mechanism is elastically biased with the plate spring or the coil springs, large flexure of the springs will apply load on the cuff by their elastic force, causing degradation of measurement accuracy.
As a blood pressure monitor provided with an automatic cuff winding mechanism attempting to solve the above-described problems, one as shown in FIG. 27 is known. In the blood pressure monitor 100E shown in FIG. 27, a main unit 110 and a living body insert portion 140 are formed in two pieces, and are connected in a pivotable manner via a pivot 145 provided on the rear end of main unit 110. With this configuration, living body insert portion 140, located on top of main unit 110 in a non-use state, is tilted backward (in a direction shown by an arrow H in the figure) as a subject 300 inserts the arm, and the inclination angle of living body insert portion 140 is adjusted in accordance with the subject's posture upon measurement. This enables accurate measurement of the blood pressure value, without restricting the posture of the subject to cause pain.
The blood pressure monitor shown in FIG. 27, however, poses an additional problem as follows. In blood pressure monitor 100E, as shown in FIG. 27, upon applying the cuff on the upper arm 320, living body insert portion 140 is tilted backward (in the direction of arrow H in the figure). This means that living body insert portion 140 moves with respect to main unit 110 in a direction opposite to the side of subject 300. As such, subject 300 is required to slouch forward to follow the movement of living body insert portion 140. Thus, as shown in FIG. 27, in order for subject 300 to apply the cuff on upper arm 320, he/she needs to slouch forward on the side of desk 210 and keep the relevant posture for several tens of seconds during the measurement. This makes subject 300 suffer pain until the end of measurement.
If the subject wants to stand erect during the measurement, instead of slouching forward, he/she needs to move blood pressure monitor 100E itself to the front end of desk 210, or move chair 220 to come closer to desk 210. Such adjustment while upper arm 320 is being inserted in the hollow opening is very tiresome, thereby imposing an unnecessary burden on subject 300.